Foam skin cream, use of the foam skin protection cream and a process of its preparation

ABSTRACT

A foam skin cream can be obtained by 
     preparing a phase I by melting at 75° C. a mixture containing fatty acids, especially C 12 -C 22  fatty acids, optionally unsaturated and/or polyunsaturated fatty acids, emulsifiers, coemulsifiers, such as triceteareth-4-phosphate, followed by metering it with stirring to a phase II temperature-controlled at 75° C. obtained from an aqueous mixture containing moisturizers, such as propylene glycol and/or polyhydric alcohols, especially glycerol, emulsifiers, such as alkyl sarcosinates, and skin care additives, such as allantoin; wherein homogeneous mixing of phases I and II is provided and said metering is performed at a temperature of 75° C.; after the metered addition, the temperature is maintained at 75° C. for a period of between 5 and 20 minutes; whereupon the temperature of the thus obtained mixture is lowered to a temperature of between 30 and 40° C. with constant stirring; the pH value is adjusted to from 7.6 to 8.2, preferably with a skin-compatible basic organic compound, and the mixture obtained is filled into dosage forms with the addition of a propellant.

The present invention relates to a foam skin cream, uses of the foamskin protection cream and a process for its preparation.

The galenic principle of an emulsoid two-phase system having lipophilicor hydrophobic components and, on the other hand, hydrophilic componentshas been known for the production of foam preparations for skin care.The application of these foam preparations to the treated skin forms atwo-dimensional two-phase network, the hydrophilic components bind tothe keratin of the horny layer and enable the evaporation of sweat whilethe lipophilic components inhibit the permeation of moisture (includingthe penetrated sweat) on the skin surface. As the foam, in contrast toother creams building a barrier, is absorbed in less than a minute, doesnot leave any grease traces on the working materials and prevents heatbuilt-up or even maceration effects from the action of sweat, the foamhas enjoyed rapidly growing popularity as a protective agent againstoccupational action of moisture. Further details about the per se knownfoam skin creams can be seen, in particular, from “Haut”, issue 4, 1992,by R. Rudolph, L. Bade, B. Brüggemann.

In “hautnah derm” 10 (1994), 344-351, B. Kunze reports lipid-containingskin protection foams which are indicated for dry sensitive skin andchronical-rhagadiform eczemas. Ingredients are also disclosed therein.The skin protection foams described therein are protective against a lotof occupational noxious matters, such as acid permanent waving liquidsin the hairdresser's trade, lyes, oils, disinfectants, cleaning andrinsing agents, but also against water, moisture, sweat, feces, urineand mineral dusts.

EP 0 598 412 also relates to skin protection foams; PTFE is described asan active principle.

DE-C-33 30 628 relates to skin protection and care-lotions containingsilicone oils, partially neutralized stearic acid, fatty alcohols andtheir ethoxylated derivatives, ethoxylated wool alcohols, cetyl/stearylalcohol, vaseline, thickeners and water. The lotions disclosed thereinare said to be quickly absorbed without leaving an annoying grease filmon the skin for extended periods of time.

Information about emulsifiers which can be employed in skin care agentsare found in DE-A-195 42 572. This reference suggests emulsifiers whichcontain from 43 to 90% by weight of alkyl and/or alkenyl oligoglycosidesand from 10 to 57% by weight of fatty alcohols. These emulsifiers areparticularly suitable for the preparation of highly viscous, sensorilylight oil-in-water emulsions having a long shelf life. The Germanutility model DE-U-9308050 relates to a skin protection foam usedagainst skin-aggressive agents. This foam consists of an aqueousemulsion containing fatty acid esters with good skin compatibility forthe production of a moisture-permeable film, polyhydric alcohol forstably dispersing the active agents and controlling the humidity of thefilm, emulsifiers for improving foam stability, surfactants for reducingthe surface tension and optionally neutralizing agents for resins andemulsifiers. Gaseous hydrocarbons may be used as propellants, forexample, propane, butane or isobutane and mixtures thereof. However, thefoams described do not contain any free fatty acids.

Aerosoles are complicated physical-chemical structures which do not formunder arbitrary circumstances. In Particular, a special balance betweenthe foam-forming components is important. Slight shifts in thecomposition may already result in a collapse of the foam; thus, aformulation of per se active substances may not be capable of beingformulated as a foam without further provisions.

Especially in occupational applications, skin creams are often foundunpleasant because the “fatting” components remain too long on the skinand lead to annoying finger traces or generally to an unpleasantfeeling. This has been remedied to some extent by the per se known skinfoams since they help preventing or reducing overload of the skin withthe fatting matters. Nevertheless, it is desirable to find even moreacceptance by the user, especially in the long-term use of skinprotection agents.

It has been the object of the present invention to extend theapplication range of skin protection foams by providing a formulationwhich is highly accepted by the user, the admixture of a wide variety ofother substances being allowed without destroying the aerosol employedor deteriorating the properties of the aerosol.

The object of the invention is surprisingly achieved by a baseformulation of a foam skin cream having the features of claim 1.Dependent claims 2 to 12 relate to preferred embodiments of the foamskin cream according to the invention. Claims 13 to 16 relate to uses ofthe foam skin cream according to the invention, whereas claim 17 relatesto a process for preparing the base of a foam skin cream according tothe invention.

The foam skin cream according to the invention can be obtained by

-   preparing a phase I by melting at 75° C. a mixture containing fatty    acids, especially C₁₂-C₂₂ fatty acids, optionally unsaturated and/or    polyunsaturated fatty acids, emulsifiers, coemulsifiers, such as    triceteareth-4-phosphate, followed by metering it with stirring to-   a phase II temperature-controlled at 75° C. obtained from an aqueous    mixture containing moisturizers, such as propylene glycol and/or    polyhydric alcohols, especially glycerol, emulsifiers, such as alkyl    sarcosinates, and skin care additives, such as allantoin;-   wherein homogeneous mixing of phases I and II is provided and said    metering is performed at a temperature of 75° C.;-   after the metered addition, the temperature is maintained at 75° C.    for a period of between 5 and 20 minutes; whereupon the temperature    of the thus obtained mixture is lowered to a temperature of between    30 and 40° C. with constant stirring;-   the pH value is adjusted to from 7.6 to 8.2, preferably with a    skin-compatible basic organic compound, and the mixture obtained is    filled into dosage forms with the addition of a propellant.

At the one hand, the product obtainable according to this process can bedirectly employed as a foam skin cream in the industrial field for theprotection from or reduction of the absorption of cancerogenicsubstances, such as polycyclic aromatic hydrocarbons. This mixture iscapable of providing effective protection for persons whose skin hasalready been exposed to cancerogenic substances, such as polycyclicaromatic hydrocarbons. In addition, the mixture is suitable forproviding protection to persons from the action of acids, lyes (notabove pH 11), scouring agents and detergents, sweat, urine, stool,rubber gloves, dusts, house dust, machine, drilling and cooling oils,greases, paints/varnishes, gypsum and other substances and chemicals,especially aggressive substances and chemicals.

The foam skin cream according to the invention contains fatty acids,especially C₁₂-C₂₂ fatty acids, and may optionally additionally containunsaturated and/or polyunsaturated fatty acids. Useful fatty acids whichare saturated include, in particular, the naturally occurring C₁₂-C₂₂fatty acids, especially stearic acid and palmitic acid. Myristic acidmay also be used. Useful unsaturated fatty acids include, in particular,those having up to three unsaturated bonds in their hydrocarbon chain.Unsaturated fatty acids are found, for example, in fractions of coconutfat. Useful coemulsifiers include per se known coemulsifiers, especiallytriceteareth-4-phosphate, sodium laureth-4-phosphate or oleth-3 andother lipophilic emulsifiers based on fatty alcohols with a low degreeof ethoxylation.

Phase I may additionally contain paraffinum liquidum. Emulsifiers to beused in phase I may include those based on fatty alcohols and thosebased on partial esters of fatty acids. Particularly preferred fattyalcohols include cetearyl alcohol. Glyceryl stearate, for example, maybe employed as a partial ester of a fatty acid.

The moisturizers to be used in phase II include, in particular,propylene glycol and/or polyhydric alcohols, such as glycerol. Asparticular emulsifiers to be used in phase II, there may be mentionedalkyl sarcosinates, such as lauroyl, lauryl, cetyl sarcosinates.

The mixture obtainable according to claim 1 also serves as a base forother foam skin creams which may be employed in a wide range ofapplications for protecting the skin and alleviating dermatologicaldysfunctions.

If desired, one or more preservatives may be added to the foam skincream according to the invention. In particular, substances such asmethyldibromoglutaronitrile and/or phenoxyethanol have proven to besuitable preservatives. These substances may be added in amounts of from0.01 to 1% by weight.

Preferably, the emulsifiers, fatty acids, coemulsifiers, moisturizersand skin care agents, especially allantoin, panthenol etc., are used inthe following amounts:

-   from 4 to 15% by weight of oil-in-water emulsifier;-   from 1 to 10% by weight of fatty acid, especially from 4 to 7% by    weight, preferably from 4.5 to 6% by weight;-   from 0.4 to 2.3% by weight of coemulsifier;-   from 1 to 10% by weight of moisturizer;-   from 0.05 to 1% by weight of skin care agent; and-   water as the balance to make 100% by weight.

A preferable foam skin cream according to the invention contains:

-   from 1 to 3% by weight of glyceryl stearate;-   from 3 to 6% by weight of cetearyl alcohol;-   from 4 to 6% by weight of stearic acid;-   from 0.5 to 2% by weight of paraffin;-   from 0.4 to 2.3% by weight of triceteareth-4-phosphate;-   from 1.5 to 4% by weight of propylene glycol;-   from 1.3 to 4.2% by weight of glycerol;-   from 1 to 3% by weight of cetyl sarcosinate;-   from 0.05 to 1% by weight of allantoin; and-   water as the balance to make 100% by weight.

In another preferred embodiment, the foam skin cream according to theinvention additionally contains a silicone-containing substance, such asdimethicone. This substance is added to phase I. Preferably, it ispresent in amounts of from 0.05 to 1% by weight.

In addition, the foam skin cream according to the invention mayadditionally contain one or more refatting substances in phase I, suchas decyl oleate, isohexadecane, stearic acid glycol ester, coconut fattyacid ethanolamide, corn oil, peanut oil, almond oil, sesame oil, oliveoil, jojoba oil, soybean oil, wool wax alcohols, paraffin, medium-chaintriglycerides, oleic acid oleyl esters, white petrolatum,macrogol-glycerol hydroxystearate, hydrogenated castor oil, castor oilfrom Ricinus communis, avocado oil, wheat germ oil, palmitic acidisopropyl ester, cetyl palmitate, myristic acid myristyl ester and/oroctyldodecanol.

In particular, the foam skin cream contains amounts of from 0.5 to 2% byweight of decyl oleate and/or from 0.5 to 2% by weight of octyldecanol,or another of the refatting substances mentioned, if the product is tobe used for normal skin. The total amount of refatting substances is tobe such that the skin protection foam is not destroyed. An amount ofabout 4% by weight of refatting substances is sufficient for normal toslightly dry skin. If dry skin is to be treated with the foam skin creamaccording to the invention, amounts of from 3 to 6% by weight of acomponent of the refatting substances, such as, in particular, decyloleate and/or octyldecanol, are recommendable. If more than onecomponent is used, the total amount of refatting components is to beabout 12% at most for slightly dry skin. If even more severely dry skinis treated, the amount of refatting substances is from about 6 to 9% byweight if a component such as decyl oleate is used, and from 6 to 9% byweight if octyldecanol is used. The amount of refatting substance maythen be up to 20% by weight.

Like the products without silicone-containing substances, the latterfoam skin creams are suitable for the care and protection of the skin,especially from aggressive substances, such as scouring agents anddetergents, sweat, urine, stool, rubber gloves, dusts, house dust,machine, drilling and cooling oils, greases, paints/varnishes, gypsumand other substances and chemicals, especially aggressive substances andchemicals.

The foam skin creams are also suitable for the treatment or alleviationof dermatological diseases. This includes, in particular, dermatologicaldiseases such as allergic contact dermatitis type I and IV,cumulative-subtoxic eczema, toxic-irritative eczema,microbial-dysregulative eczema, atopic dermatitis, atopic palmoplantareczema, dyshidrosis, hyperhidrosis, contact urticaria, intertriginouseczema in connection with hemorrhoids, various weeping fungalinfections, e.g., interdigital mycosis, perleches, psoriasis vulgaris,ulcus cruris, cholinergic urticaria, diaper dermatitis.

It may be indicated to include substances which can increase themoisture content of the skin, in addition to refatting substances. Suchhydratizing substances include, in particular, urea, ethoxydiglycol,sodium chloride, magnesium chloride, sorbitol, dexpanthenol, sodiumlactate, allantoin, hyaluronic acid, vitamin E, linolenic acid. Theamount of those substances can be from 1 to 20% by weight or more of therespective substances, depending on the severity of the disease to betreated. These quantities also apply, in particular, to urea which mayalso be present in amounts of from 3 to 15% by weight or from 12.5 to15% by weight. The foam skin cream according to the invention may alsobe used for psoriasis.

One particularly important field of application concerns the prophylaxisand treatment of diabetic foot. Due to accompanying symptoms ofdiabetes, diabetics suffer from dry skin which in the course of thediseases favors damage to the extremities, up to an extent whereamputation becomes necessary in the case of those having been diabeticfor many years. Prophylactic application of skin protection agents whichprovide an improvement of the skin parameters in diabetics can preventthe development of diabetic foot.

In addition, skin care substances, such as polyunsaturated fatty acids(PUFA), may be added to the foam skin cream according to the invention.These include, in particular, omega-6 fatty acids as known, for example,from evening primrose oil and borage oil. Both synthetic omega-6 fattyacids and those obtained from the mentioned plant extracts may beemployed.

Further, there may be used soothing substances, such as chamomileextract, as another fraction which may be admixed with the foam skincream according to the invention.

Skin-active vitamins, such as vitamins A, E and F, may be admixed withthe foam skin cream according to the invention in effective amounts.Especially for the treatment and prevention of diaper dermatitis,admixing the following substances has proven useful: from 3 to 7% byweight of Calendula extract, from 3 to 7% by weight of Hamamelisextract, from 3 to 7% by weight of chamomile extract, from 3 to 7% byweight of tea tree oil extract, from 1 to 5% by weight of decyl oleate,from 1 to 5% by weight of octyldodecanol.

The process according to the invention for the preparation of the foamskin protection cream according to the invention comprises the followingsteps:

-   preparing a phase I by melting at 75° C. a mixture containing fatty    acids, especially C₁₂-C₂₂ fatty acids, optionally unsaturated and/or    polyunsaturated fatty acids, coemulsifiers, such as    triceteareth-4-phosphate, followed by metering this phase with    stirring to-   a phase II molten at 75° C. obtained from an aqueous mixture    containing moisturizers, such as propylene glycol and/or polyhydric    alcohols, especially glycerol, emulsifiers, such as alkyl    sarcosinates, and skin care additives, such as allantoin;-   wherein homogeneous mixing of phases I and II is provided and said    metering is performed at a temperature of 75° C.;-   after the addition of phase I to phase II, the temperature is    maintained at 75° C. for a period of between 5 and 20 minutes;    whereupon the temperature of the thus obtained mixture is lowered to    a temperature of between 30 and 40° C. with constant stirring;-   adjusting the pH value to from 7.6 to 8.2, preferably with a    skin-compatible basic organic compound, and filling into containers    with the addition of a propellant.

The invention will be further illustrated by the following Example.

EXAMPLE

The skin protection cream according to the invention is prepared in aheatable and coolable closed apparatus with a self-withdrawinghomogenisator and a heatable metering funnel (preferably in a Korumamultipurpose apparatus).

The preparation of phase I is effected in a heatable metering funnel bymelting at 75° C. a mixture containing 2% by weight of glycerylstearate, 4% by weight of cetearyl alcohol, 5% by weight of stearicacid, 1% by weight of paraffin and 1% by weight oftriceteareth-4-phosphate, followed by metering this phase with stirringto phase II previously prepared in the heatable and coolable closedapparatus with a self-withdrawing homogenisator. Phase II consists of anaqueous mixture containing 2.5% by weight of propylene glycol, 2.5% byweight of glycerol, 2% by weight of sodium lauroylsarcosinate and 0.3%by weight of allantoin. The amount of water is 79.7% by weight.Homogeneous mixing of phases I and II is to be provided.

The metering of phase I is performed at a temperature of 75° C. Bothphases are combined with constant stirring at a medium stirring speed,and care must be taken that homogenization is effected uniformly. Thetemperature is maintained at 75° C. for between 5 and 20 min. Themixture obtained is cooled to a temperature of between 30 and 40° C.with constant stirring.

Then, after a temperature of 40° C. has been reached, the furthersubstances may be added. This may include adjusting the pH value tobetween 7.8 and 8.0. For this purpose, 2-amino-2-methyl-1-propanol isused. Stirring is continued for a sufficient period of time until the pHvalue has stabilized, followed by filling into suitable storage tanks orinto the corresponding spraying containers. In the latter case, 91% ofdrug is filled together with 9% of butane/propane.

1-17. (canceled)
 18. A foam aerosol skin cream, wherein the skin creamdoes not contain PTFE, obtained by preparing a phase I by melting at 75°C. a mixture containing one or more C₁₀-C₂₂ fatty acids, optionallycontaining an unsaturated or polyunsaturated fatty acid, an emulsifier,or a coemulsifier or a mixture thereof; preparing a phase II,temperature-controlled at 75° C., by aqueous admixture of urea, as amoisture-binding agent, and two or three ingredients selected from thegroup consisting of a moisturizer, an emulsifier, and a skin careadditive, and a combination thereof; metered addition with homogenousmixing of phase I and phase II at a temperature of 75° C.; followed bymaintaining the temperature of the homogeneous mixture at 75° C. for aperiod of between 5 and 20 minutes; followed by lowering the temperatureof the homogeneous mixture from 75° C. to a temperature between 30° C.and 40° C. with constant stirring; followed by adjusting the pH of thehomogeneous mixture at a temperature between 30° C. and 40° C. to avalue of 7.6 to 8.2; followed by combining the homogeneous mixture witha propellant in a dosage form, wherein the propellant is butane,propane, or a mixture thereof.
 19. The foam aerosol skin cream accordingto claim 18, wherein phase I further contains as a coemulsifiertriceteareth-4-phosphate.
 20. The foam aerosol skin cream according toclaim 18, wherein the moisturizer in phase II is propylene glycol, apolyhydric alcohol, or a combination thereof.
 21. The foam aerosol skincream according to claim 18, wherein the moisturizer in phase II isglycerol and the emulsifier in phase II is an alkyl sarcosinate.
 22. Thefoam aerosol skin cream according to claim 18, wherein the skin careadditive in phase II is allantoin.
 23. The foam aerosol skin creamaccording to claim 18, wherein the pH is adjusted to a value from of 7.6to 8.2 by adding a skin-compatible basic organic compound.
 24. The foamaerosol skin cream according to claim 18, further comprising adding apreservative to the homogeneous mixture, with stirring, at thetemperature of 30° C. to 40° C.
 25. The foam aerosol skin creamaccording to claim 18, containing from 4 to 15% by weight ofoil-in-water emulsifier; from 1 to 10% by weight of the C₁₀-C₂₂ fattyacid; from 0.4 to 2.3% by weight of the coemulsifier; from 1 to 20%urea; from 1 to 10% by weight of the moisturizer; from 0.5 to 1% byweight of the skin care additive; and water as the balance to make 100%by weight.
 26. A process for making the foam aerosol skin creamcomprising: preparing a phase I by melting at 75° C. a mixturecontaining one or more C₁₀-C₂₂ fatty acids, optionally containing anunsaturated or polyunsaturated fatty acid, an emulsifier, or acoemulsifier or a mixture thereof; preparing a phase II,temperature-controlled at 75° C., by aqueous admixture of urea, as amoisture-binding agent, and two or three ingredients selected from thegroup consisting of a moisturizer, an emulsifier, and a skin careadditive, and a combination thereof; metered addition with homogenousmixing of phase I and phase II at a temperature of 75° C.; followed bymaintaining the temperature of the homogeneous mixture at 75° C. for aperiod of between 5 and 20 minutes; followed by lowering the temperatureof the homogeneous mixture from 75° C. to a temperature between 30° C.and 40° C. with constant stirring; followed by adjusting the pH of thehomogeneous mixture at a temperature between 30° C. and 40° C. to avalue of 7.6 to 8.2.
 27. The foam aerosol skin cream made by the processaccording to claim
 26. 28. A process of making a container of spray foamaerosol cream comprising filling the foam aerosol cream of claim 27together with a propellant into a spray-can container, wherein thepropellant is butane, propane, or a mixture thereof.